Toys and the like which provide some form of action, particularly a repeating complex motion of some sort, are generally fascinating to people, particularly to younger children. Relatively simple means of providing such action in an unpowered toy has been developed in the past, as will be discussed in the Description of the Prior Art following. These toys rely upon a mass which is free to shift its position longitudinally within the body of the toy, as the body tumbles end over end down a slope. The resulting action is a repeating end over end action, generally with some delay in each half revolution due to the time it takes for the enclosed mass to roll from one end of the body to the other. However, persons will generally quickly tire of watching such a toy, due to the consistent rate of the tumbling action. With a body of fixed length, and an internal weight of fixed mass, the tumbling rate cannot be varied and will remain constant.
What is needed is a tumbling toy which provides for changes of the length of the body (particularly the internal length traveled by the moving mass within), and/or the mass contained within, in order to adjust the moment of inertia of the toy to provide different tumbling rates. The toy must provide for simple and rapid adjustment of length and/or internal mass, so that the adjustment may be made by children playing with the toy, rather than requiring intervention by an adult or older person.